## 14.4. Reserved Number Register Names

The following number register names are used by the ms package. An italicized n means that the name contains a numeral (generally the interpolated value of another number register).

`n` `T` | `AJ` | `AV` | `BC` | `BD` | `BE` | `BH` | `BQ` | `BW`
`CW` | `EF` | `FC` | `FL` | `FM` | `FP` | `GA` | `GW` | `H1`
`H2` | `H3` | `H4` | `H5` | `HM` | `HT` | `I0` | `IF` | `IK`
`IM` | `IP` | `IR` | `IS` | `IT` | `IX` | `I` `n` | `J` n | `KG`
`KI` | `KM` | `L1` | `LE` | `LL` | `LT` | `MC` | `MF` | `MG`
`ML` | `MM` | `MN` | `NA` | `NC` | `ND` | `NQ` | `NS` | `NX`
`OJ` | `PD` | `PE` | `PF` | `PI` | `PN` | `PO` | `PQ` | `PS`
`PX` | `QI` | `QP` | `RO` | `SJ` | `ST` | `T.` | `TB` | `TC`
`TD` | `TK` | `TN` | `TQ` | `TV` | `TY` | `TZ` | `VS` | `WF`
`XX` | `YE` | `YY` | `ZN` |  |  |  |  |

When you're writing your own macros, the safest bet is to use mixed-case letters for macro names. (Using uppercase letters could conflict with reserved ms names, and using lowercase letters could conflict with `troff` requests.)

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